Disturbing video here from Freehold (N.J.) Raceway, but know that four drivers went to the hospital and all horses survived.

The pace car skidded on a slick—though reportedly not icy—track in the day's fifth race, spinning into the path of the horses as they entered the first turn. The gate was still extended, and only the leader of the seven-horse field made it through unscathed.

"We don't know what happened. It was definitely a freak mishap. Something I've never seen in 40 years in racing," said Freehold Raceway director of facing and race secretary Karen Fagliarone.